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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 653 · 40 sums
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The method (Split into easy parts): (a + b)² = a² + 2ab + b². (a − b)² = a² − 2ab + b². (a + b)(a − b) = a² − b²; so a² − b² = (a + b)(a − b). a² + b² = (a + b)² − 2ab = (a − b)² + 2ab.

NameDateTime takenScore ___ / 40
  1. 1.If a + b = 5 and ab = 6, what is a² + b²?
  2. 2.Use (a + b)² = a² + 2ab + b² to find 41².
  3. 3.Use a² − b² = (a + b)(a − b) to find 51² − 21².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 42².
  5. 5.If a − b = 5 and ab = 24, what is a² + b²?
  6. 6.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  7. 7.Find the value of x² − 2xy + y² when x = 9 and y = 6.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 74².
  9. 9.Use a² − b² = (a + b)(a − b) to find 73² − 23².
  10. 10.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  11. 11.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 86².
  13. 13.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  14. 14.Use a² − b² = (a + b)(a − b) to find 20² − 9².
  15. 15.Use a² − b² = (a + b)(a − b) to find 68² − 62².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 26².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 62².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 83².
  19. 19.Use a² − b² = (a + b)(a − b) to find 83² − 44².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 95².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 92².
  22. 22.If a + b = 9 and ab = 18, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 68² − 24².
  24. 24.Use a² − b² = (a + b)(a − b) to find 36² − 7².
  25. 25.If a − b = 3 and ab = 28, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 41² − 28².
  27. 27.Find the value of x² − y² when x = 5 and y = 1.
  28. 28.If a + b = 7 and ab = 6, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 11².
  30. 30.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 12².
  32. 32.Use a² − b² = (a + b)(a − b) to find 96² − 43².
  33. 33.Use a² − b² = (a + b)(a − b) to find 52² − 6².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 51².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 51².
  36. 36.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  37. 37.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 19².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 74².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 57².

Answer key

  1. 13
  2. 1681
  3. 2160
  4. 1764
  5. 73
  6. 4896
  7. 9
  8. 5476
  9. 4800
  10. 9999
  11. 169
  12. 7396
  13. 1
  14. 319
  15. 780
  16. 676
  17. 3844
  18. 6889
  19. 4953
  20. 9025
  21. 8464
  22. 45
  23. 4048
  24. 1247
  25. 65
  26. 897
  27. 24
  28. 37
  29. 121
  30. 8091
  31. 144
  32. 7367
  33. 2668
  34. 2601
  35. 2601
  36. 319
  37. 25
  38. 361
  39. 5476
  40. 3249

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